We've never had this problem before, in all the houses we've lived:
We've been here for about four years now and just moved the bed for my spring cleaning: the wall behind the bed head has a huge black stain on it!
I tried to wipe it clean but its not helping,
it's actually worse now as I've scrubbed some of the paint off
We didn't even have to bleach it- it started disappearing as soon as we moved the bed and would probably be gone in the next few weeks.
Should we re-paint the wall now?
Is there a special type of paint to prevent this problem?
From the British Coatings Federation web site they say this:
It is certainly not worth simply painting over any mould patches as the patches will reappear. The cause of the dampness needs to be found and treated, and then sterilised either using a fungicidal solution or a 3:1 mixture of water and household bleach. It is then important to leave the area for at least a week to check for any reappearance of mould before repainting. It is then advisable to coat with a paint containing a fungicide. Remember to avoid splashes of fungicide on the skin and accidental consumption by children and animals.
My thanks to them for phrasing it so well.
This sounds like mould growing where condensation forms. Do you live in an old, poorly insulated home?
I live in an old Victorian house with solid (ie no cavity) walls that get very cold in winter. When warm, damp air (moisture from breath, cooking, showering etc) comes into contact with them, condensation forms, especially in rooms with less heating or behind furniture. Behind almost every piece of furniture in the bedroom and spare room, the walls became completely black with mould over the winter. It was quite a shock to move a cupboard and find the wall behind black.
Mould remover took most of it off, though it did still leave a slight stain. But it's always going to come back if the condensation problem is still there. Better ventilation helps and so does more heating, but I've never really solved the problem, so I'll be glad to move!
This definitely sounds like mould to be, bit too much moisture in the air. Moving the bed could help but remember to check your furnishing. If you have a latex mattress on your bed, you should be ok but other types could harbour mould and bacteria that is going to affect your health. If you want to patch it, get some anti mould paint which is a little pricey but ok. A dehumidifer is probably going to be your best bet to tackle the problem with minimal fuss though